System for monitoring and reporting medical measurements

ABSTRACT

A system for monitoring and reporting medical information includes a stand-alone monitor for storing data records comprising measured values and time stamps and for transmitting the records to a remote reporting unit over a communication system. The remote reporting unit includes a relational data base that is updated when records are down-loaded from the monitor; a report generator for generating chronological graphs of the measured values for a particular patient; and a report transmitting unit for transmitting reports to a requesting health care provider.

This is a Continuation of application Ser. No. 08/579,062, filed on Dec.22, 1995, now U.S. Pat. No. 5,549,117, which is a Divisional ofApplication No. 08/247,727, now abandoned filed on May 23, 1994.

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure as it appears in the Patent and TrademarkOffice patent file or record, but otherwise reserves all copyrightrights whatsoever.

BACKGROUND OF THE INVENTION

Recent developments in medical device technology have led to thedevelopment of low cost devices for measuring physiologicalcharacteristics of a patient suffering from a chronic disease. As aresult of these measurements marked improvements in treatment arepossible because the type of treatment is responsive to the result of ameasurement.

As an example, diabetes patients now measure blood sugar several times aday to determine when to administer insulin and how much insulin isrequired. Management of other chronic diseases could require monitoringmultiple physiological measurement including pulse rate, blood pressure,respiration rate, body weight, spirometric parameters, etc.

Unfortunately, however, the possibilities of the improved technologyoften have not been realized because of patient inability to use thedevice, or understand the meaning of the device output. Often, effectivetreatment requires that measurements be taken over time and plotted on agraph to determine patient tendencies and the oncoming of a crisis.There are also problems on the health care provider side, with increasedphysician workload preventing the physician from monitoring complianceand gathering, formatting data, and interpreting data.

The following is a detailed discussion of the problems inherent intreating chronic asthma. Recent events suggest that there is an abundantneed for data collection and reporting tools for use in the treatment ofchronic asthma. The U.S. National Center for Health Statistics estimatesthat 12 million Americans--nearly 5% of the population--have asthma.Asthma morbidity and mortality rates increased dramatically during the1980's. The reasons for these increases are not well understood. In the1980's leading medical researchers began to view asthma as primarily aninflammatory response in the airways rather than bronchospasm.Consequently, they began advocating a new pharmacological therapy,anti-inflammatory medications. Furthermore, numerous studies of selfmanagement programs have documented the importance of early warningdetection and patient-physician cooperative management in the long-termtreatment of chronic asthma.

In August 1991 the National Asthma Education Program (NAEP), which wasorganized by the National Institutes of Health, published its ExpertPanel Report: "Guidelines for the Diagnosis and Management of Asthma".In its foreword the Expert Panel Report states: "People with asthma canexpect to control their symptoms, prevent asthma episodes, be physicallyactive, and breathe normally. This report presents guidelines to helpclinicians and patients meet these goals of asthma care." The reportsuggests regimens for pharmacological therapy, emphasizes the role ofanti-inflammatory medication, and warns about the risks of over- andunder-medication. The report stresses the importance of fostering apartnership among patient, family, and physician in the achievement of asuccessful self-management program for asthma sufferers.

Peak Flow Meters and Asthma Management

Peak flow meters have been around for a number of years. Many cliniciansrecognize that daily PEFR measurements can provide early warnings of anasthma attack. However, self-management programs which urge daily peakflow monitoring continue to be the exception rather than the rule. Inadvocating a preventative approach to asthma care, the National AsthmaEducation Program is urging clinicians and patients to adopt apreventative rather than an interventional approach to managing asthma.

The peak flow meter measures Peak Expiratory Flow (PEF), defined as themaximum rate at which an individual can expel air from the lungs, usingmaximal effort from full inhalation. PEF is measured in liters perminute. The highest value obtained in up to three attempts is recordedinto a peak flow diary, which is usually a handwritten chart.

The personal spirometer typically measures several respiratoryparameters, including the Forced Expiratory Volume (FEV₁), defined asthe volume of air expelled by an individual in the first second ofexhalation, using maximal effort from full inhalation. FEV₁ is measuredin liters.

Physicians can gain several advantages by having access to accuraterespiratory status data:

in evaluating the efficacy of the current medication regimen

in detecting seasonal patterns, a rising or falling personal best, PEFand FEV₁ trends

in assessing airway stability over large blocks of time

in assessing compliance with the self management program, includingdaily peak flow monitoring

in providing a basis for an incentive system that physicians and/orparents can use to reward good compliance

According to the Expert Panel Report, PEF and FEV₁ are useful indetecting the early signs of airway instability and in evaluating theefficacy of medication regimens. For instance, a patient can take PEFsamples before and after administering a bronchodilator and thus have abasis upon which to evaluate the drug's efficacy in treating thatpatient's acute asthma episodes.

The Expert Panel Report is attempting to steer primary care physicianstoward supporting patient self-management programs that entail dailypeak flow monitoring. It recommends that patients 5 years or older withmoderate or severe asthma measure their peak expiratory flow rates on adaily basis. Furthermore, it recommends that all patients and physiciansemploy peak flow meters and/or personal spirometers in their self asthmamanagement programs.

The chairman of the NAEP's Expert Panel, Albert L. Sheffer, M.D.,expressed his concerns about inadequacies in many home managementprograms for asthma: "All asthma patients who need daily therapy shouldbe monitored with a peak flow meter. Meters are now used on fewer than25% of those patients."

Guillermo R. Mendoza, M.D., a renowned expert in asthma diagnosis andtreatment, made this statement: "Since 1978, despite a growing consensusabout the value of peak flow monitoring, only a minority of primary careproviders in the U.S. have adopted peak flow in their office practice.Few high risk asthma patients in this country have peak flow meters athome or know how to use them effectively."

A U.S. government publication makes this recommendation: "Ask yourdoctor about using a peak flow meter. A peak flow meter can tell youwhen an episode is coming--even before you feel symptoms. Takingmedicine before you feel symptoms can stop the episode. People over age4 with moderate or severe asthma should use a peak flow meter at leastdaily."

Prior Art: Mechanical Peak Flow Meters

In mechanical peak flow meters, the breath displaces a string-retardeddeflector, which moves a pointer along a scale to indicate the testresults. Most mechanical meters are simply pieces of molded plastic thathave relatively poor inter-device accuracy and reproducibility. In theirday these devices were useful to obtain fairly accurate readings,particularly where relative performance was more useful than absoluteresults. The creation of a longitudinal record depended solely on thediscipline and care exercised by the user. Several examples of themechanical type are listed below.

Prior Art: Electronic Peak Flow Meters and Spirometers

In the earliest models of electronic peak flow meters and personalspirometers, designers merely substituted a pneumotach sensor for thespring-retarded deflector in the mechanical device. All models use amicroprocessor to handle the computations and a liquid crystal displayto present the numerical test results.

Although current models of portable electronic spirometry devices offermore measurements and good reliability than mechanical peak flow meters,they offer little improvement to the practical challenge of maximizingthe utility of home spirometry for both the user and the physician.Their many shortcomings are listed below.

1. They are expensive because their designs are not inherently low cost.

2. They fail to minimize the inconvenience of daily monitoring regimensby not creating a memory-resident longitudinal record which isimmediately accessible via the device's human interface.

3. They do not present any trend information by showing the results ofpreceding tests.

4. They do not deliberately focus the user's attention on airway statusand trend; their human interfaces are poorly suited for use by smallchildren.

5. They do not allow the user to label some test results as postmedication results.

6. They do not provide the user with a low cost mechanism to deliver theclinical information to the physician in a timely and efficient manner.

7. They do not provide the physician with a crisp, graphical reportdesigned to facilitate a sound, rapid interpretation and good medicaltreatment decisions.

8. They fail to shield the physician from needing a computer to collectand review data.

9. They do not address physicians' need to track compliance with themanagement plan nor a systematic method for reviewing the efficacy ofthe asthma management plan.

10. They do not provide for the systematic collection of test resultsfor statistical analysis.

SUMMARY OF THE INVENTION

One aspect of the present invention is a reporting system that achievesan economical method of collecting, processing, and disseminatingclinical data obtained by individuals in the course of practicing theircoordinated care plan prepared by their physician to aid in thelong-term management of chronic disease. A hands-free, two-waycommunications link between a physician and patient for use in handlinga chronic disease is established.

According to another aspect of the invention, a new "programming" addsnew information to the link between physical and patient in a low-costperipheral that enables collection and dissemination of measured data ina low-cost and efficient manner.

According to another aspect of the present invention a unique monitoringsystem creats, documents, and reports a chronological record of statusinformation of a physiological characteristic. The only burden on thepatient is to take measurements at prescribed times.

According to one aspect of the invention, the monitoring system includesa monitor module for use by the patient, and a remote reporting system.The monitor module includes a processor, a memory, and a time stampgenerator and stores low density medical information, comprising datarecords including the value of a measured characteristic and a timestamp indicating when the characteristic was measured, in the memory.The module includes an interface and a communication protocol fortransferring the low density medical information to the reportgenerating system over the communication system.

According to a further aspect of the invention, the reporting systemincludes a relational data base storing patient records includingmeasured values and time stamps. When data records are downloaded from aremote module the patient record is updated with the latest datarecords. The transmission of measurement data from the device to thereporting system can cause or trigger the production and transmission ofa report to the patient's physician.

According to still further aspect of the invention, a report request isreceived from a health provider over the communication system for aparticular patient and provided to the reporting system. The reportingsystem accesses the patient record, generates a report showing thechronological record of the measured characteristic in graphical formatand transmits the report to the health care professional over thecommunication system.

According to a still further aspect of the invention, a user interfaceincludes display areas corresponding to zones of respiratoryperformance. When a respiratory function is measured the zone ofperformance corresponding to the present measurement is determined andthe corresponding display zone is activated.

According to a still further aspect of the invention, a low-costrespiratory function sensor includes a sensor chamber having acylindrical part and a mouthpiece part. The mouthpiece is oriented todirect air flow tangentially against the outer circular surface of thecylindrical part and the cylindrical part has a rotor mounted thereinwhich rotates when a patient blows into the mouthpiece.

According to a still further aspect of the invention, the rotor has acentral section oriented along the axis of rotation and rotor bladesextending from the central section to intercept tangential air flow atthe circular boundary of cylindrical part. A bar magnet is disposed inthe central section and a coil is utilized to generate pulses inresponse to the changing magnetic field when the rotor spins.

Additional features and advantages of the invention will be apparent inview of the following detailed description and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram of the measuring, monitoring, andreporting system;

FIG. 2 is a block diagram of the software architecture of the reportingsystem;

FIG. 3 is a block diagram of the hardware architecture of the monitor;

FIGS. 4A-4D2 are diagrams depicting the user interface;

FIGS. 5A, 5B, and 5C are views of the monitor housing;

FIGS. 6A and 6B are views of the sensor chamber;

FIGS. 7A and 7B are views of the assembly;

FIG. 8 is a cross-sectional view of the sensor chamber;

FIG. 9 is a block diagram of the respiratory flow measuring system; and

FIGS. 10A-10J are graphs depicting chronological records of respiratoryfunction.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 depicts a functional overview of the measuring, monitoring, andreporting system of the present invention. A sensor device 10 is used tomeasure the value of a selected physiological characteristic of apatient such as respiratory functions, e.g., peak expiratory flow (PEF)and forced expiratory volume (FEV₁), blood glucose levels, bloodpressure, heart rate, body weight, fluid intake and discharge rates, andcaloric intake. Sensors for measuring these values and providing adigital sensor output encoding the measured values of the physiologicalcharacteristics are commercially available. A particular sensor formeasuring respiratory functions will be described-more fully below.

The intelligence and communications functions are provided in a monitormodule 12 which is used by the patient. The sensor may be integratedinto the monitor module 12 or be separate with a cable or other means,e.g., an IR beam, used to transfer the digital sensor output to themonitor module 12. The monitor module 12 performs the intelligencefunctions of collection and interpretation of measured values encoded inthe digital sensor outputs, the memory function of storing multiplemeasured values along with time stamps indicating when measurements weretaken, the display function of visually communicating the interpretedmeasurements to the patient, and the communication function fortransferring measured values and time stamps via the telephone system.The intelligence and communication functions may be separated intodifferent modules in other embodiments.

A remote reporting system 14, coupled to the monitor module 12 by thetelephone system, performs the functions of receiving the informationtransmitted from the monitor module 12, of updating a database oflongitudinal patient records to add the information transferred from themonitor module 12 to the record of the patient utilizing the monitormodule 12, of generating patient reports in graphical formats, and ofcommunicating the reports to physicians or patients. Thus, reports arefaxed to the physician to emulate a "medical telegram" and the physicianis shielded from needing a computer to collect and review data. Althoughan initial preferred embodiment will provide delivery by fax, a reportof a given patient's data can be delivered to one or more physicians bytelephone facsimile, electronic mail, broadcast data communications, orregular mail service. Likewise, the patient can receive a copy of thereport by similar means.

FIG. 2 is a block diagram of the software architecture of the remotereporting system 14. The core of the system of is a relational database20 for storing longitudinal patient records, including measured valuesand time stamps provided by the monitor module 12, and analysisalgorithms 22 for manipulating the records and data in the database. Thelongitudinal records include unique ID codes pairing a patient and aremote sensor and a subscription pairing a device ID with a careprovider.

A data manager 24 interfaces the data base 20 to various input/outputblocks and control blocks such as an Interactive Voice Response System25. This interactive voice response system allows medical professionalsto submit requests for reports based on selections from a menu of reporttypes. Inbound data from a monitor module 12 is received at an InboundDataCom Front End 26 which interfaces to the telephone system and thedata is transferred to the inbound data port of the data manager 24through an Inbound Communications Server 28.

An outbound data port of the data manager 24 is connected to a reportgenerator 30. The report generator outputs reports via a fax server 32and Outbound Communications Server 34. Additionally, a second outputport transfers electronic patient records to HMO Information Centers 36.Thus, the longitudinal records can be electronically transferred tofacilities having computer resources to process the data to generatereports or the reports themselves can be transmitted to individualphysicians without requiring the intervention of a computer.

FIG. 3 is a block diagram of the functionality of the monitor module 12.The monitor module 12 is controlled by a single-chip micro-controller40, such as a Motorola MC 6805, that includes on-chip memory for storingapplication programs and other data. The micro-controller 40 interfaceswith the other functional blocks utilizing standard data, address, andcontrol buses which are not part of the invention. The interconnectionof the micro-controller 40 and functional blocks is depictedschematically in the figure. As depicted, the micro-controller includeson-board digital signal processing algorithms, program memory, a dateand time clock, and a display driver.

The micro-controller 40 receives sensor output digital data 41 when apatient measures the value of a physiological characteristic and forms adata record encoding the value of the measured characteristic, a timestamp indicating the time and date when the measurement is taken, andunique ID code, which is the serial number of the individual devicestored within its internal circuitry, identifying the monitor module 12.Data records are stored in a RAM 42 as a circular file. The internalfile structure of a "data record" has its own specialized, embeddedinstruction set that identifies several data types, includingmeasurement values, time and date, personal best value, and zoneboundary values. If the RAM 42 is full then a most recent data recordwill be written over the oldest data record.

The micro-controller 40 also responds to the user tagging a single testwith a visual marker in the display. The tag is inserted as an extraelement into a data record in the device memory. The physician caninstruct the patient to mark individual test results as"post-medication" tests according to certain rules. When the tag is usedin this manner, i.e., as a post-medication marker, the reporting systemcan provide reports that show the patient's response to medication(e.g., the response to a bronchodilator).

The micro-controller is also programmed to implement a set-up procedureallowing the user to choose between two settings for the session length,0 and 10. When the session length is set to 0, the device stores theresult of every measurement into its long-term memory. When the sessionlength is set to 10, the device stores the best PEF and FEV1 valuesachieved in a ten minute interval, which begins with the first blow in apotential series of blows. The session lengths are varied so that thegeneral use of the device could conform with currently accepted practiceof performing up to three blows in a test session and documenting onlythe best result of the three. Thus, the device provides for performingthe Peak Expiratory Flow test in accordance with guidance published bythe National Asthma Education Program and the American Thoracic Society.

A telephone interface 44 is controlled by the micro-controller totransfer records from the RAM 42 to the remote reporting system 14.

When the patient wishes to down-load data records from the monitormodule 12 the patient connects a telephone line to an RJ-11C telephonejack in the telephone interface 44 and simply pushes a button on theuser interface. The micro-controller then executes an applicationprogram to retrieve data records from the RAM 42, convert the digitaldata to analog signals, and control the telephone interface circuit toconnect the remote reporting system 14 and to transfer the retrieveddata records to the remote reporting system 14.

In the preferred embodiment, a modem chip is not used to transfer datain order to avoid the extra cost of including another chip. Instead, themicro-controller 40 executes custom application software to drivespecialized circuitry to perform a binary file transfer to the remotecomputer at 300 Baud according to the Bell 103 standard. Error detectionis achieved by using the cyclic redundancy checking during the binaryfile transfer. In other embodiments the file transfer scheme may beimplemented to use a faster data rate (e.g., 1200 Baud) and a differentBell standard (e.g., bell 201 or 212).

FIGS. 4A-4C depict a special user interface 50, controlled bymicro-controller 40, that presents the result of a measurement ofrespiratory functions in terms of peak flow zones.

To help patients manage their asthma, the Expert Panel Report publishedby the NIH presents the system of peak flow zones. In the zone modeleach test result is expressed as a percent of one's Personal Best,defined as the highest peak flow level that the user normally achieveswhen his or her airway is clear. The zones are analogous to trafficlight signals--i.e. green, yellow and red--to make it easier toremember. Each zone identifies a percentage of the Personal Best. TheGreen Zone is 80%-100% of the Personal Best; the Yellow Zone is 50%-80%;and the Red Zone is less than 50% The personal best and boundariesbetween the zones are configurable values that can be adjusted by thepatient. Any adjustments should be made with the specific approval ofthe physician.

The display 50 has three rows 52, 54, and 56 of rectangular displayareas formed thereon. The bottom row 52 of display areas is red, tocorrespond to the red zone, the middle row 54 of display areas isyellow, to correspond to the yellow zone, and the top row 56 of displayareas is green, to correspond to the green zone.

In a preferred embodiment, the zone chart consists of a five row by ninecolumn array of dots. The green zone 56 and yellow zone 54 each have tworows of dots on the zone chart portion of the display 50. The two rowsbisect'the zones to provide better resolution. Thus, if the green zone56 covers 80 to 100% of the personal best, the lower corresponds to 80to 90% and the upper row to 90 to 100%. Similarly, if the yellow zone 54covers 50 to 80% of the personal best, the lower corresponds to 50 to65% and the upper row to 65 to 80%.

The micro-controller 40 selectively activates the display areas of thedisplay 50. A personal best data record is stored in the RAM 42 alongwith zone defining values. When the micro-controller 40 receives adigital sensor output it executes an application program to retrieve thepersonal best data record and zone defining values from the RAM 42 andto determine which zone includes the value encoded in the receiveddigital sensor output.

The micro-controller 40 then activates the farthest right display areaof the row of display area corresponding to the zone that includes themeasured value. Thus, the user is immediately informed whether themeasured value is in the red, yellow, or green zone and does not needany familiarity or understanding of numerical values.

Other characteristics of the display are illustrated in FIGS. 4A-4D2.For example, display areas to the left of the rightmost display area ineach row display the zone including previously measured values. Thus,the patient can see whether his performance is improving ordeteriorating over time. Additionally, an animated character's (theWelby character) arm is moved when the present measured value switcheszones to highlight the change of the zone to the patient. Numericdisplays may also be activated. The micro-controller 40 includesapplication programs responsive to the user input to activate thevarious display areas of the display 50.

The human interface of the monitor was designed to facilitate use bychildren and adults. It has several important facets:

only three buttons for simplicity of operation; its display device (anLCD) employs multiple functional areas listed below;

a number line for reporting measurement results and calculated values,

a zone chart for reporting zone status using position-and-color codeddots,

an animated character, "Welby", whose actions and expressions reinforcethe meaning of the reported airway status information, and

various symbols which annotate items of information presented on otherparts of the display (e.g., units of measurement such as Liters/minute,Liters, AM, PM, the personal best crown, the red zone cross, thetelephone) or which convey specific messages (e.g., the low batteryindicator).

When the results of a measurement are reported to the patient on thedevice's display, the information is presented in several waysconcurrently. The presentation of information in each functional area ofthe display is designed to maximize the probability that the user willcomprehend the meaning of the display and will remember or know how tolook up the appropriate action to take given the patient's currentairway status.

Another unique aspect of the display format is breaking up thepresentation of results from a single test into separate frames to avoidmaking the display too complicated or busy and thus rendering it lesseffective. The device presents the complete data for each blow in asequence of two or more frames on the display, depending on whichelements of data are desired. The standard review uses two frames whichpresent different data elements on the number line: 1) the peak flow inliter/minute and percent of personal best; and 2) the date and time ofmeasurement. Each frame also included the activated zone chart, theWelby character, and various symbols. The optional review, which isactivated by pressing the center button, adds a third frame whichincluded the FEV1 in liters.

As depicted in FIG. 4D, the various configurations of the Welbycharacter are used in the written coordinated care program that aphysician typically prepares for a patient. A given configuration of theWelby character is used as a label adjacent to the description of thetherapy prescribed for instances in which the patient's airway status iswithin a given zone.

A preferred embodiment of a sensor/monitor module assembly will now bedescribed with reference to FIGS. 5A-5C, 6A-6B, 7A-7B, and 8. As will beapparent from the following description, the monitor/module is astand-alone device useful to asthma patients for monitoring theircondition. Referring to FIG. 5A, a monitor housing 60 includes top andbottom plates 62 and 64. FIGS. 5B and 5C are front and back views,respectively, of the top plate 62. The front surface has the LCD display50 and user input buttons 46 disposed thereon. Turning to FIG. 5C, aprojection 64 at the bottom part of the top plate 62 includes a circularpart 64c and a mouthpiece storing part 64m. The projection is borderedby a projection edge 66 having an arc-shaped portion 66c and amouthpiece abutting portion 66m. Additionally, a mounting post 68 isdisposed at the center of the circular part 64c of the projection 64 anda coil housing 69 is disposed on the circular part 64c displacedslightly from the center.

FIGS. 6A and 6B are top and bottom views of a sensor chamber 70.Referring to FIG. 6A, the chamber 70 includes a cylindrical chamber part72 and a mouthpiece part 74. The cylindrical chamber part 72 has acircular cross-section with an axial connector 76 formed at the centerof the top surface of the cylindrical section and an arc-shaped coilhousing aperture 77, centered at the axial connector 76 and displacedradially therefrom, formed in the top surface of the cylindrical chamberpart 74. Sets of vent holes are formed in the top and bottom surfaces ofthe cylindrical chamber part 74 and are disposed along a circular pathcentered disposed near the outer circumference of the cylindricalchamber part 74.

FIGS. 7A-7B depict the monitor module/sensor assembly with the sensorhousing 70 in the closed position. The mounting post 68 on theprojection 66 is registered with the axial connector 76 so that thesensor chamber 70 rotates about the mounting post from a closed position(shown) to an open position (phantom). In the closed position theopening of the mouthpiece part 74 abuts the mouthpiece abutting section66m of the projection edge 66 to seal of the mouthpiece. In the openposition the patient seals his lips about the opening of the mouthpieceand blows into the chamber to measure air flow. The mouthpiece rotatesbetween the open and closed positions to help keep out lint and debris.

The operation of the sensor to measure PEF and FEV₁ will now bedescribed with reference to FIGS. 8 and 9. FIG. 8 is a cross-sectionalview of the cylindrical chamber part 72. The bottom and top interiorsurfaces have bearing receptor cups 80t and 80b formed therein. A rotor82 includes a central post 84 with rotor blades 86 extending therefrom.The rotor blades 86 include vertical vanes 88 disposed near thecylindrical side surface of the cylindrical section 72. Pointed bearings90t and 90b are formed on the top and bottom of the central post 84 andregister with the bearing receptor notches 80t and 80b. The central post82 includes at least one bar magnet 92 shown in cross-section in theFigure.

The rotor within the sensor includes two sub-assemblies: the four-bladedrotor 82 and the cylindrical magnet 92, which fits permanently into therotor's shaft so that the long axis of the magnet is perpendicular tothe rotor's axis of rotation. The tips 88 of the rotor's shaft fitloosely into small cups 80t and 80b in the interior surface of the topand bottom sub-assemblies of the sensor. There are no bearings involvedin this junction; the tips of the rotor's shaft rest in these smallcups.

When a patient blows into the sensor chamber, the rotor spins like atop, with the tips of its shaft turning within the cups. In the eventthat sputum or mucus gets lodged in or around these pivot points, theloose fit of the tip of the rotor shaft into the cups allows for easycleaning under a stream of tap water.

When a patient blows into the mouthpiece opening of the sensor housing70 the air flow is directed against the cylindrical side wall of thechamber 70 and impinges on blades 88 to cause rotation of the rotor.About 30 milliliters of air pass through the chamber 70 for eachrotation of the rotor. The air exits through the vent holes 78 toprevent the build-up of back pressure. The sensor chamber 72 ismechanically designed to achieve a vortical flow when the patient blowsinto it. Furthermore, note that the four-bladed rotor spins around itsmaximum principal moment of inertia, just like a top, therebyeliminating the potential for bearing chatter and drag.

FIG. 9 is a particular implementation of the generalized system depictedin FIG. 3 for utilizing the sensor depicted in FIG. 8. In FIG. 9, thecoil 69 generates two pulses each time the bar magnet 92 completes arotation. The pulses are amplified and filtered to produce digitaltransitions. The time between each transition is processed by themicrocontroller 40 executing application software. The PEF and FEV₁ arecalculated and stored in the RAM 42 as a part of a data record.

From FIG. 8 is seen that the rotation bearing is a "sloppy bearing" notrequiring a high precision fit. Thus, all parts of the sensor can bemanufactured of plastic utilizing low-cost processes. Additionally, themolding process produces consistent parts, thereby assuring very highdevice-to-device reproducibility and permitting different sensorchambers (mouthpieces) to be used with any given monitor housing.Moreover, in-the-field calibration of a mouthpiece is not required.

The "sloppy bearing" results in small timing errors from one pulse tothe next. Measurements are made on the basis of several pulses so thatsuch effects are averaged out. Additionally, the microcontrollerexecutes a digital compensation program to eliminate the effect of thenon-zero moment of inertia. The program is based on several parameterswhich are matched to the actual rotational dynamics and aerodynamics ofthe rotor and chamber.

The rotor 80 has a top-like rotation characteristic when rotated aboutthe central post and a non-zero moment of inertia. The micro-controllerexecutes a compensation program to eliminate the effect of the non-zeromoment and to calculate the actual value of the PEF and FEV. The programis based on the physical principles involved in calculating the motionof the rotor and includes several parameters which are matched to theactual rotation of the rotor.

FIG. 10 depicts several exemplary graphical formats for reportingrespiratory function trends to a physician. These formats illustrate howthe simple actions of periodically blowing into the mouthpiece of thesensor and downloading the data to the remote reporting system resultsin charts showing the respiratory performance of the patient.

Thus, a system for coordinated management of chronic diseases orlong-lasting conditions, such as asthma or other lung disease, diabetes,hypertension, and obesity is described. The sensor and monitor interactto eliminate the errors inherent in the current manual process ofmeasuring (misreading error); documenting (incorrect transcription,incomplete transcription); and reporting (omission error) achronological record of physiological status information. Additionally,the system fosters compliance with a physiological status monitoringprogram agreed upon by both the patient and physician as component of anoverall self-management program for chronic disease or other longlasting conditions. Compliance information can serve as the basis forincentive programs targeted at both patients and physicians. Theseincentive programs could help motivate patients to comply with themonitoring program and to learn about how to maintain control over thechronic condition. They could also help motivate physicians to work athelping their patients maintain control over the chronic condition.Improvement in compliance is usually achieved by making improvementsthat render a monitoring tool more convenient, easier to use, and moreunderstandable.

The invention has been described with reference to the preferredembodiments. Alternatives and substitutions will now be apparent topersons of ordinary skill in the art. The dial protocol from the devicecan be either tone or pulse. Other approaches to the design of thesensor could include multi-pole magnets, multiple coils, smaller orlarger sensor chambers (depending on the measurement of interest),optical interrupters and other magnetic sensors (e.g., Hall effectswitch, Reed relay and magneto-resistive). When the device transfers acopy of its measurement data record to a remote computer the device maydial the telephone number of the remote computer. The dialing activitymay be configured to be compatible with older rotary type of telephoneservice (pulse) or with contemporary touch-tone type of telephone (tone)Additionally, the link between the monitor and remote computer could beconfigured either as a wired link, e.g., cable and connectors, a basestation in which the monitor rests making electrical contacts, or awireless link, e.g., radio, infra-red, or acoustic. Accordingly, it isnot intended to limit the invention except as provided by the appendedclaims.

What is claimed is:
 1. A respiratory function sensor comprising:a sensorchamber forming an enclosed volume and having an opening into theenclosed volume; a rotor, rotatably mounted within the enclosed volumeand having a plurality of blades and a shaft mounted vertically withinsaid sensor chamber, for rotating in response to a volume of air exhaledby a patient through the opening in the enclosed volume, with each rotorblade including a vane, displaced horizontally from said shaft, to forman open area between the shaft and vane; a magnet, disposed within saidshaft for generating a rotating magnetic field when the patient exhalesinto the opening; and a magnetic pick-up, disposed within said chamber,in proximity to said magnet, and positioned to be located within theopen area when said rotor is rotating, said magnetic pick-up forgenerating electromagnetic pulses in response to the rotating magneticfield, with the frequency of pulses indicating the rate of exhalation ofthe patient.